TURBOJET ENGINE COMPRISING A NACELLE EQUIPPED WITH REVERSE FLAP

Abstract

TURBOJET ENGINE COMPRISING A NACELLE EQUIPPED WITH REVERSER FLAPPERS The invention relates to a dual-flow turbojet engine (100) with a nacelle (102) having a longitudinal axis (X) and comprising a front frame (206), a movable cowl (207a), at least two reverser flaps (104) articulated on the movable cowl (207a) and an operating mechanism (250) with a first arm (252) articulated on the front frame (206), a second arm (258) articulated on the movable cowl (207a), a third arm (256) mounted articulated on the second arm (258), a fourth arm (254) articulated on the third arm (256) and the first arm (252), two fittings (260) articulated on the third arm (256), and a connecting shaft (264) articulated on the fitting (260) where a shaft (262) of each reversing flap (104) is articulated on the connecting shaft (264) by a ball joint (264b). With such an arrangement, the space requirement is reduced. Fig. 4

Description

Title of the invention: TURBOJET ENGINE COMPRISING A NACELLE EQUIPPED WITH REVERSE FLAP Technical field

[0001] The present invention relates to a dual-flow turbojet engine which comprises a nacelle equipped with a plurality of reversing flaps and an improved operating mechanism, as well as an aircraft comprising at least one such dual-flow turbojet engine. STATE OF THE PRIOR ART

[0002] An aircraft has a fuselage on each side of which a wing is fixed. Under each wing is suspended at least one dual-flow turbojet engine. Each dual-flow turbojet engine is fixed under the wing by means of a mast which is fixed between the wing structure and the structure of the dual-flow turbojet engine.

[0003] The dual-flow turbojet engine comprises an engine and a nacelle which is fixed around the engine. Outside air enters the dual-flow turbojet engine at an air inlet at the front, then it separates into a primary flow which feeds the engine and a secondary flow which flows between the engine and the nacelle in a secondary vein.

[0004] The nacelle comprises a plurality of reversing flaps, each being movable between a closed position in which it comes into continuity with the outer surface of the nacelle and an open position in which it opens a window in the wall of the nacelle to expel the air of the secondary flow to the outside.

[0005] The reversing flap is mounted to be able to rotate on the structure of the nacelle so as to move from a closed position where the reversing flap does not block the secondary flow stream to an open position where the reversing flap blocks the stream and diverts part of the secondary flow towards the outside through the window.

[0006] The movement of each reversing flap is controlled by one or more actuators which are relatively heavy and bulky.

[0007] Although the mechanism of such a reversing flap gives complete satisfaction, it is desirable to find different mechanisms. Statement of the invention

[0008] An object of the present invention is to provide a dual-flow turbojet engine which comprises a nacelle equipped with a plurality of reversing flaps with a different operating mechanism.

[0009] To this end, a dual-flow turbojet engine is proposed comprising an engine and a nacelle surrounding the engine, where a secondary vein of a secondary flow is delimited between the nacelle and the engine, said nacelle having a longitudinal axis and comprising:

[0010] - a fixed front frame,

[0011] - a movable hood which is movable in translation relative to the front frame according to a translation direction between an advanced position in which the movable cowl is brought closer to the front frame and a retracted position in which the movable cowl is moved away from the front frame to define between them an open window between the secondary vein and the exterior of the nacelle,

[0012] - at least two reversing flaps, each being mounted articulated on the movable hood between a closed position in which it closes an area of ​​the window and an open position in which it does not close said area of ​​the window and extends across the secondary vein,

[0013] - a set of actuators where each is mounted between the front frame and the hood mobile, and designed to ensure, from the advanced position, a translational movement of the mobile hood to the retracted position and vice versa, and

[0014] - for a pair of two neighboring reversing flaps, an operating mechanism comprising:

[0015] - a first arm having a first end and a second end, where the first end is mounted articulated on the front frame around a first axis of rotation orthoradial to the longitudinal axis,

[0016] - a second arm having a first end and a second end, where the first end is mounted articulated on the movable cover around a second axis of rotation orthoradial to the longitudinal axis,

[0017] - a third arm having a first end and a second end, where the first end is mounted articulated on the second end of the second arm around a third axis of rotation orthoradial to the longitudinal axis,

[0018] - a fourth arm having a first end and a second end, where the first end is mounted articulated on the second end of the third arm around a fourth axis of rotation orthoradial to the longitudinal axis, and where the second end is mounted articulated on the second end of the first arm around a fifth axis of rotation perpendicular to the fourth axis of rotation,

[0019] - for each reversing flap of the pair, a fitting mounted hinged on the third arm around a sixth axis of rotation perpendicular to the third axis of rotation, and

[0020] - for each reversing flap of the pair, a connecting shaft of which a first end is mounted articulated on the fitting around a seventh axis of rotation perpendicular to the sixth axis of rotation,

[0021] where for each reversing flap of the pair, a shaft of said reversing flap is mounted articulated on a second end of the connecting shaft by a ball joint and where the axis of the shaft is orthoradial relative to the longitudinal axis.

[0022] Such a turbojet engine makes it possible, among other things, to improve aerodynamic performance by reducing the size of the opening mechanism.

[0023] Advantageously, in the forward position, the axes of rotation extend from front to rear in the following order: the first axis of rotation, the second axis of rotation, the third axis of rotation and the fourth axis of rotation and where the second end of the fourth arm is forward relative to the first end of the fourth arm, and in the retracted position, the axes of rotation extend from front to rear in the following order: the first axis of rotation, the fourth axis of rotation, the third axis of rotation, the second axis of rotation, and where the second end of the fourth arm is forward relative to the first end of the fourth arm.

[0024] Advantageously, the shaft is composed of a first sub-shaft and a second sub-shaft integral with each other, the first sub-shaft is mounted articulated on the second end of the connecting shaft by the ball joint and the second sub-shaft is mounted articulated on the reversing flap around an eighth axis of rotation.

[0025] Advantageously, the first sub-tree and the second sub-tree are offset from each other.

[0026] Advantageously, the shaft comprises a pallet, and the operating mechanism comprises a spring damper, a first end of which is mounted articulated on the pallet and the second end of which is mounted articulated on the reversing flap.

[0027] Advantageously, the connection between the second end of the fourth arm and the second end of the first arm has a degree of freedom in translation parallel to the fifth axis of rotation, the operating mechanism comprises a constraint spring arranged between the fourth arm and the first arm and arranged so as to push the first arm away from the fourth axis of rotation.

[0028] Advantageously, the first arm forms a hood and in the advanced position, the first arm covers the elements of the operating mechanism.

[0029] Advantageously, the operating mechanism comprises elastic pads fixed on the third arm and arranged to come against the movable hood in the advanced position.

[0030] Advantageously, in the advanced position, the first arm has an extension which covers the edges of the neighboring reversing flaps.

[0031] The invention also proposes an aircraft comprising at least one dual-flow turbojet engine according to one of the preceding variants. Brief description of the drawings

[0032] The above-mentioned features of the invention, as well as others, will appear more clearly on reading the following description of an exemplary embodiment, said description being made in relation to the attached drawings, among which:

[0033] [Fig.l] is a side view of an aircraft comprising a turbojet engine according to the invention,

[0034] [Fig.2] is a perspective view of a part of the turbojet according to the invention in advanced position,

[0035] [Fig.3] is a perspective view identical to that of [Fig.2] in the retracted position and open,

[0036] [Fig.4] is a sectional view through a radial plane of the turbojet according to the invention in advanced position,

[0037] [Fig.5] is a sectional view through a radial plane of the turbojet according to the invention in retracted and open position,

[0038] [Fig.6] is a view of the front of the turbojet according to the invention in the retracted position. and open,

[0039] [Fig.7] is a view of the rear of the turbojet according to the invention in the retracted position. and open,

[0040] [Fig.8] is a view of the rear of the turbojet according to the invention in the retracted position. and open,

[0041] [Fig.9] is a sectional view through a plane parallel to a longitudinal axis of the turbojet according to the invention,

[0042] [Fig. 10] is a detail view of an operating mechanism implemented in the turbojet according to the invention, and

[0043] [Fig. 11] is a detailed view of an alternative embodiment of the invention.

[0044] DETAILED DESCRIPTION OF EMBODIMENTS

[0045] In the following description, the terms relating to a position are taken with reference to an aircraft in the forward position as shown in [Fig.l] and where the arrow 107 shows the direction of forward movement of the aircraft in flight. The terms "upstream" and "downstream" are with reference to the direction of airflow in the nacelle.

[0046] [Fig. 1] shows an aircraft 50 which comprises a fuselage 51 on each side of which is fixed a wing 52 which carries at least one dual-flow turbojet engine 100 according to the invention. The dual-flow turbojet engine 100 is fixed under the wing 52 by means of a mast 53.

[0047] [Fig.2] and [Fig.3] show a part of the dual-flow turbojet engine 100 which has a nacelle 102 and an engine 20 (in dotted lines in [Fig.l]) which is housed inside the nacelle 102 and which has a fan casing at the front.

[0048] In the following description, and by convention, X is the longitudinal axis of the dual-flow turbojet 100 which is parallel to the longitudinal axis of the aircraft 50 or roll axis, oriented positively in the direction of advancement of the aircraft 50, Y is the transverse axis which is parallel to the pitch axis of the aircraft 50 which is horizontal when the aircraft 50 is on the ground, and Z is the vertical axis which is parallel to the axis of yaw when the aircraft 50 is on the ground, these three directions X, Y and Z being orthogonal to each other.

[0049] The dual-flow turbojet 100 has, between the nacelle 102 and the engine 20, a secondary vein 202 in which circulates a secondary flow 208 of air coming from an air inlet through a fan. The longitudinal axis X is also the longitudinal axis of the nacelle 102.

[0050] The nacelle 102 has a fixed structure which is fixedly mounted for example on the fan casing and which here comprises a front frame 206 mounted around and at the rear of the fan casing.

[0051] The nacelle 102 also has a mobile assembly 207 which has a mobile cover 207a forming, among other things, the walls of the nozzle through which the gases escape from the nacelle 102 from the rear.

[0052] The movable cowl 207a is movable in translation relative to the front frame 206 in a translation direction parallel to the longitudinal axis X between an advanced position ([Fig.2]) in which the movable cowl 207a is brought closer to the front frame 206 and a retracted position ([Fig.3]) in which the movable cowl 207a is moved away from the front frame 206 to define between them a window 210 open between the secondary vein 202 and the exterior of the nacelle 102. The front frame 206 delimits the window 210 upstream relative to the longitudinal axis X and the movable cowl 207a delimits the window 210 downstream relative to the longitudinal axis X.

[0053] The secondary flow 208 can then escape through the window 210 which extends around the circumference of the nacelle 102.

[0054] In the embodiment of the invention presented here, the nacelle 102 also has cascades 209 which are integral with the fixed structure 206 and are arranged across the window 210. The cascades 209 are made up of deflectors allowing the redirection of the flow passing from the inside to the outside and more particularly to the front.

[0055] The translation of the movable cover 207a is carried out by any conventional slide system between the fixed structure and the movable cover 207a.

[0056] The nacelle 102 also comprises at least two reversing flaps 104 where each is mounted articulated on the movable cowl 207a between a closed position ([Fig.2]) in which it closes a zone of the window 210 and an open position ([Fig.3]) in which it does not close said zone of the window 210 and extends across the secondary vein 202. The reversing flaps 104 are distributed on the periphery of the nacelle 102 as a function of the angular opening of the window 210 around the longitudinal axis X.

[0057] The movements of the reversing flaps 104 from the closed / open position to the open / closed position are carried out when the movable hood 207a passes from the advanced / moved back to the retracted / forward position by installing an operating mechanism 250 for each pair of two neighboring reversing flaps 104.

[0058] The operating mechanism 250 is thus provided to move each reversing flap 104 from the closed position to the open position when the movable hood 207a moves from the forward position to the retracted position and vice versa.

[0059] [Fig. 4] to 10 show different views of the operating mechanism 250 and [Fig. 11] shows an alternative embodiment.

[0060] Each reversing flap 104 is mounted to rotate on the movable cover 207a by means of two hinges 280 which are more visible in [Fig.7] and which have the same hinge axis. The hinges 280 are arranged along an upstream edge of the reversing flap 104 while the opposite free edge is positioned downstream in the closed position and towards the engine 20 in the open position.

[0061] Each hinge 280 here takes the form of a female yoke secured to the movable cover 207a and a male yoke secured to the reversing flap 104. The male yoke is inserted into the female yoke and is fixed there by the installation of a securing shaft.

[0062] The movement of the movable cowl 207a relative to the front frame 206 is achieved by the installation of a set of actuators 218, such as double-acting cylinders, where each is mounted between the front frame 206 and the movable cowl 207a. Each actuator 218 ensures, from the forward position, a translational movement of the movable cowl 207a to the retracted position and vice versa. Each actuator 218 is controlled by a control unit, for example of the processor type, which controls the movements in one direction or the other according to the needs of the aircraft 50.

[0063] As mentioned above, there is an operating mechanism 250 for two reversing flaps 104 arranged next to each other and the operating mechanism 250 is arranged between them.

[0064] The operating mechanism 250 comprises a first arm 252 which has a first end and a second end. The first end of the first arm 252 is mounted in an articulated manner, in particular rotatably movable, on the front frame 206 around a first axis of rotation 252a which is orthoradial relative to the longitudinal axis X.

[0065] The first arm 252 is mounted to rotate on the front frame 206 by means of two hinges 282 which have the same hinge axis coincident with the first axis of rotation 252a. The hinges 282 are arranged at the first end of the first arm 252 which is upstream while the second free end is oriented downstream. Each hinge 282 here takes the form of a female yoke secured to the first arm 252 and a male yoke secured of the front frame 206. The male yoke fits into the female yoke and is fixed there by the installation of a securing shaft.

[0066] In the embodiment of the invention presented here, the first arm 252 takes the form of a hood which is arranged so that in the advanced position, the first arm 252 covers the other elements of the operating mechanism 250 which are described below. In the advanced position, the other elements are positioned between the movable hood 207a and the first arm 252 in the form of a hood. The latter thus separates the other elements of the secondary flow 208 to protect them and to form an aerodynamic surface in the secondary vein 202.

[0067] The operating mechanism 250 comprises a second arm 258 which has a first end and a second end. The first end of the second arm 258 is mounted articulated, in particular rotatably, on the movable cover 207a around a second axis of rotation 258a orthoradial to the longitudinal axis X.

[0068] The second arm 258 is mounted to rotate on the movable cover 207a by means of two hinges 284 which have the same hinge axis coinciding with the second axis of rotation 258a. The hinges 284 are arranged at the first end of the second arm 258 which, in the retracted / open position, is downstream while the second end is oriented upstream.

[0069] The operating mechanism 250 comprises a third arm 256 which has a first end and a second end. The first end of the third arm 256 is mounted articulated, in particular rotatably movable, on the second end of the second arm 258 around a third axis of rotation 256a orthoradial to the longitudinal axis X.

[0070] The third arm 256 is mounted to rotate on the second arm 258 by means of a hinge 286. The hinge 286 is arranged at the first end of the third arm 256 which, in the retracted / open position, is downstream while the second end is oriented upstream. The hinge 286 here takes the form of a female yoke secured to the third arm 256 and a male yoke secured to the second arm 258. The male yoke is inserted into the female yoke and is fixed there by the installation of a securing shaft.

[0071] The operating mechanism 250 comprises a fourth arm 254 which has a first end and a second end. The first end of the fourth arm 254 is mounted articulated, in particular rotatably movable, on the second end of the third arm 256 around a fourth axis of rotation 254a orthoradial to the longitudinal axis X.

[0072] Furthermore, the second end of the fourth arm 254 is mounted articulated, in particular movable in rotation, on the second end of the first arm 252 around of a fifth axis of rotation 254b perpendicular to the fourth axis of rotation 254a.

[0073] The fourth arm 254 is mounted to rotate on the third arm 256 by means of a hinge 288. The hinge 288 is arranged at the first end of the fourth arm 254, in the retracted / open position, is downstream while the second end is oriented upstream. The hinge 288 here takes the form of a female yoke secured to the third arm 256 and a male yoke secured to the fourth arm 254. The male yoke is inserted into the female yoke and is fixed there by the installation of a securing shaft.

[0074] The fourth arm 254 is mounted to be able to rotate on the first arm 252 by means of a pivot connection 290.

[0075] For each reversing flap 104 of the pair, the operating mechanism 250 comprises a fitting 260 mounted in an articulated manner, in particular movable in rotation, on the third arm 256 around a sixth axis of rotation 260a perpendicular to the third axis of rotation 256a. There are therefore two fittings 260 mounted on the third arm 256, each via a pivot connection 292 around the sixth axis of rotation 260a.

[0076] Here each fitting 260 has a barrel 294 fitted around a rotation shaft 296 secured to the third arm 256.

[0077] For each reversing flap 104 of the pair, the operating mechanism 250 comprises a connecting shaft 264, a first end of which is mounted articulated, in particular movable in rotation, on the fitting 260 around a seventh axis of rotation 264a perpendicular to the sixth axis of rotation 260a.

[0078] Each connecting shaft 264 is rotatably mounted by means of a pivot connection 298 produced by two bearings coaxial with the seventh axis of rotation 264a and integral with the fitting 260 and in each of which the connecting shaft 264 is rotatably mounted. The two connecting shafts 264 are positioned in a V around the sixth axis of rotation 260a and the movement of each fitting 260 allows adaptation to a three-dimensional displacement.

[0079] Each connecting shaft 264 is thus movable in rotation around the sixth axis of rotation 260a and the seventh axis of rotation 264a.

[0080] For each reversing flap 104 of the pair, the operating mechanism 250 also comprises a shaft 262 linked to said reversing flap 104, and mounted articulated on a second end of the connecting shaft 264 by a ball joint 264b and where the axis of the shaft 262 is orthoradial relative to the longitudinal axis X.

[0081] The operating mechanism 250 is thus arranged so as to fold into the forward / closed position to save space and to unfold into the retracted / open position. As shown in [Fig. 4], in the forward / closed position, the elements of the mechanism 250 operating mechanism folds back on itself and as shown in [Fig.5], in the retracted / open position, the elements of the operating mechanism 250 unwind and stretch along the longitudinal axis X.

[0082] Furthermore, the operating mechanism 250 is arranged between two reversing flaps 104 to also save space.

[0083] When folding the operating mechanism 250, the third arm 256 passes behind the second arm 258 and at the same time the fittings 260 oscillate around the sixth axis of rotation 260a and the connecting shafts 264 oscillate around the seventh axis of rotation 264a.

[0084] The movement of each connecting shaft 264 causes the reversing flap 104 to move via the shaft 102.

[0085] In the proposed embodiment of the invention, in the forward position, the axes of rotation extend from front to rear in the following order: the first axis of rotation 252a, the second axis of rotation 258a, the third axis of rotation 256a and the fourth axis of rotation 254a and where the second end of the fourth arm 254 is forward relative to the first end of the fourth arm 254, and in the retracted position, the axes of rotation extend from front to rear in the following order: the first axis of rotation 252a, the fourth axis of rotation 254a, the third axis of rotation 256a, the second axis of rotation 258a and where the second end of the fourth arm 254 is forward relative to the first end of the fourth arm 254.

[0086] In the embodiment variant of [Fig. 11], the shaft 262 is mounted integral with the reversing flap 104.

[0087] In the embodiment of the invention of Figs. 4 to 10, the shaft 262 is composed of a first sub-shaft 263a and a second sub-shaft 263b which are integral with each other and extend each other. The two sub-shafts 263a-b are orthoradial with respect to the longitudinal axis X.

[0088] The first sub-shaft 263a is mounted articulated on the second end of the connecting shaft 264 by the ball joint 264b and the second sub-shaft 263b is mounted articulated, in particular mobile in rotation, on the reversing flap 104 around an eighth axis of rotation 262a.

[0089] The second sub-shaft 263b is mounted in rotation by means of a pivot connection 300 produced by two bearings coaxial with the eighth axis of rotation 262a and integral with the reversing flap 104 and in each of which the second sub-shaft 263b is mounted in rotation.

[0090] In the embodiment of the invention shown in [Fig. 10] in particular, the first sub-shaft 263a and the second sub-shaft 263b are offset from each other, i.e. parallel to each other but whose axes are not coaxial. In In this case, the eighth axis of rotation 262a is the axis of the second sub-shaft 263b. The offset between the sub-shafts 263a-b makes it possible to achieve an eccentric movement.

[0091] More particularly in this latter case, the shaft 262 comprises a pallet 266 which here ensures the junction between the first sub-shaft 263a and the second sub-shaft 263b. The operating mechanism 250 comprises a spring damper 268, a first end of which is mounted articulated on the pallet 266 and the second end of which is mounted articulated on the reversing flap 104. The spring damper 268 here comprises two sliders mounted to move relative to each other, one of which is connected to the pallet 266 and the other of which is connected to the reversing flap 104 and a compression spring which tends to separate the two sliders.

[0092] As shown more clearly in [Fig. 5], the connection between the second end of the fourth arm 254 and the second end of the first arm 252 has a degree of freedom in translation parallel to the fifth axis of rotation 254b in order to absorb changes in position during deployment / folding of the operating mechanism 250.

[0093] The operating mechanism 250 also comprises a constraint spring 270, typically a compression spring, disposed between the fourth arm 254 and the first arm 252 and arranged so as to push the first arm 252 away from the fourth axis of rotation 254a. The constraint spring 270 allows for adaptation in length.

[0094] To absorb shocks and play in the advanced / closed position, the operating mechanism 250 comprises elastic pads 272 fixed to the third arm 256 and arranged to come against the movable hood 207a in the advanced position. The elastic pads 272 are arranged here at the second end of the third arm 256.

[0095] As shown in [Fig.2], in the advanced / closed position, the first arm 252 may have an edge parallel and slightly distant from the edge of the reversing flap 104, but the first arm 252 may also have an extension 274 which covers the edges of the neighboring reversing flaps 104 for an aerodynamic gain.

[0096] Each reversing flap 104 also has at least one elastic contact pad 302 for coming into contact against the movable hood 207 in the advanced / closed position.

Claims

1. Claims Double-flow turbojet (100) comprising an engine (20) and a nacelle (102) surrounding the engine (20), where a secondary vein (202) of a secondary flow (208) is delimited between the nacelle (102) and the engine (20), said nacelle (102) having a longitudinal axis (X) and comprising: - a fixed front frame (206), - a movable cowl (207a) which is movable in translation relative to the front frame (206) in a translation direction between an advanced position in which the movable cowl (207a) is brought closer to the front frame (206) and a retracted position in which the movable cowl (207a) is moved away from the front frame (206) to define between them a window (210) open between the secondary vein (202) and the exterior of the nacelle (102), - at least two reversing flaps (104), each being mounted articulated on the movable cover (207a) between a closed position in which it closes an area of ​​the window (210) and an open position in which it does not close said area of ​​the window (210) and extends across the secondary vein (202), - a set of actuators (218) where each is mounted between the front frame (206) and the movable hood (207a) and designed to ensure, from the advanced position, a translational movement of the movable hood (207a) to the retracted position and vice versa, and - for a pair of two neighboring reversing flaps (104), an operating mechanism (250) comprising: - a first arm (252) having a first end and a second end, where the first end is mounted articulated on the front frame (206) around a first axis of rotation (252a) orthoradial to the longitudinal axis (X), - a second arm (258) having a first end and a second end, where the first end is mounted articulated on the movable cover (207a) around a second axis of rotation (258a) orthoradial to the longitudinal axis (X), - a third arm (256) having a first end and a second end, where the first end is mounted articulated on the second end of the second arm (258) around a third axis of rotation (256a) orthoradial to the longitudinal axis (X), - a fourth arm (254) having a first end and a second end, where the first end is mounted articulated on the second end of the third arm (256) around a fourth axis of rotation (254a) orthoradial to the longitudinal axis (X), and where the second end is mounted articulated on the second end of the first arm (252) around a fifth axis of rotation (254b) perpendicular to the fourth axis of rotation (254a), - for each reversing flap (104) of the pair, a fitting (260) mounted articulated on the third arm (256) around a sixth axis of rotation (260a) perpendicular to the third axis of rotation (256a), and - for each reversing flap (104) of the pair,a connecting shaft (264) a first end of which is mounted articulated on the fitting (260) around a seventh axis of rotation (264a) perpendicular to the sixth axis of rotation (260a), where for each reversing flap (104) of the pair, a shaft (262) of said reversing flap (104) is mounted articulated on a second end of the connecting shaft (264) by a ball joint (264b) and where the axis of the shaft (262) is orthoradial relative to the longitudinal axis (X).,

2. A dual-flow turbojet engine (100) according to claim 1, characterized in that in the forward position, the axes of rotation extend from front to rear in the following order: the first axis of rotation (252a), the second axis of rotation (258a), the third axis of rotation (256a) and the fourth axis of rotation (254a) and where the second end of the fourth arm (254) is forward relative to the first end of the fourth arm (254), and in that in the retracted position, the axes of rotation extend from front to rear in the following order: the first axis of rotation (252a), the fourth axis of rotation (254a), the third axis of rotation (256a), the second axis of rotation (258a) and where the second end of the fourth arm (254) is forward relative to the first end of the fourth arm (254).

3. Double-flow turbojet (100) according to one of claims 1 or 2, characterized in that the shaft (262) is composed of a first sub-shaft (263a) and a second sub-shaft (263b) integral with one another. the other, in that the first sub-shaft (263a) is mounted articulated on the second end of the connecting shaft (264) by the ball joint (264b) and in that the second sub-shaft (263b) is mounted articulated on the reversing flap (104) around an eighth axis of rotation (262a).

4. A dual-flow turbojet engine (100) according to claim 3, characterized in that the first sub-shaft (263a) and the second sub-shaft (263b) are offset relative to each other.

5. Double-flow turbojet (100) according to one of claims 3 or 4, characterized in that the shaft (262) comprises a vane (266), and in that the operating mechanism (250) comprises a spring damper (268) of which a first end is mounted articulated on the vane (266) and of which the second end is mounted articulated on the reversing flap (104).

6. Double-flow turbojet (100) according to one of claims 1 to 5, characterized in that the connection between the second end of the fourth arm (254) and the second end of the first arm (252) has a degree of freedom in translation parallel to the fifth axis of rotation (254b), in that the operating mechanism (250) comprises a constraint spring (270) disposed between the fourth arm (254) and the first arm (252) and arranged so as to push the first arm (252) away from the fourth axis of rotation (254a).

7. Double-flow turbojet (100) according to one of claims 1 to 6, characterized in that the first arm (252) forms a cover and in that in the advanced position, the first arm (252) covers the elements of the operating mechanism (250).

8. Double-flow turbojet (100) according to one of claims 1 to 7, characterized in that the operating mechanism (250) comprises elastic pads (272) fixed on the third arm (256) and arranged to come against the movable cowl (207a) in the advanced position.

9. Double-flow turbojet (100) according to one of claims 1 to 8, characterized in that in the advanced position, the first arm (252) has an extension (274) which covers the edges of the neighboring reverser flaps (104).

10. Aircraft (50) comprising at least one dual-flow turbojet (100) according to one of the preceding claims.

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